US20150191198A1 - Friction Brake Mechanism and Associated Steering Column - Google Patents
Friction Brake Mechanism and Associated Steering Column Download PDFInfo
- Publication number
- US20150191198A1 US20150191198A1 US14/149,309 US201414149309A US2015191198A1 US 20150191198 A1 US20150191198 A1 US 20150191198A1 US 201414149309 A US201414149309 A US 201414149309A US 2015191198 A1 US2015191198 A1 US 2015191198A1
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- US
- United States
- Prior art keywords
- steering
- steering system
- brake mechanism
- steering shaft
- engaged position
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D5/00—Power-assisted or power-driven steering
- B62D5/001—Mechanical components or aspects of steer-by-wire systems, not otherwise provided for in this maingroup
- B62D5/003—Backup systems, e.g. for manual steering
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D1/00—Steering controls, i.e. means for initiating a change of direction of the vehicle
- B62D1/02—Steering controls, i.e. means for initiating a change of direction of the vehicle vehicle-mounted
- B62D1/16—Steering columns
- B62D1/18—Steering columns yieldable or adjustable, e.g. tiltable
- B62D1/184—Mechanisms for locking columns at selected positions
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D1/00—Steering controls, i.e. means for initiating a change of direction of the vehicle
- B62D1/02—Steering controls, i.e. means for initiating a change of direction of the vehicle vehicle-mounted
- B62D1/22—Alternative steering-control elements, e.g. for teaching purposes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D1/00—Steering controls, i.e. means for initiating a change of direction of the vehicle
- B62D1/24—Steering controls, i.e. means for initiating a change of direction of the vehicle not vehicle-mounted
- B62D1/28—Steering controls, i.e. means for initiating a change of direction of the vehicle not vehicle-mounted non-mechanical, e.g. following a line or other known markers
- B62D1/286—Systems for interrupting non-mechanical steering due to driver intervention
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D5/00—Power-assisted or power-driven steering
- B62D5/001—Mechanical components or aspects of steer-by-wire systems, not otherwise provided for in this maingroup
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D5/00—Power-assisted or power-driven steering
- B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
- B62D5/043—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by clutch means between driving element, e.g. motor, and driven element, e.g. steering column or steering gear
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D65/00—Designing, manufacturing, e.g. assembling, facilitating disassembly, or structurally modifying motor vehicles or trailers, not otherwise provided for
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05G—CONTROL DEVICES OR SYSTEMS INSOFAR AS CHARACTERISED BY MECHANICAL FEATURES ONLY
- G05G5/00—Means for preventing, limiting or returning the movements of parts of a control mechanism, e.g. locking controlling member
- G05G5/06—Means for preventing, limiting or returning the movements of parts of a control mechanism, e.g. locking controlling member for holding members in one or a limited number of definite positions only
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05G—CONTROL DEVICES OR SYSTEMS INSOFAR AS CHARACTERISED BY MECHANICAL FEATURES ONLY
- G05G5/00—Means for preventing, limiting or returning the movements of parts of a control mechanism, e.g. locking controlling member
- G05G5/06—Means for preventing, limiting or returning the movements of parts of a control mechanism, e.g. locking controlling member for holding members in one or a limited number of definite positions only
- G05G5/08—Interlocking of members, e.g. locking member in a particular position before or during the movement of another member
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05G—CONTROL DEVICES OR SYSTEMS INSOFAR AS CHARACTERISED BY MECHANICAL FEATURES ONLY
- G05G5/00—Means for preventing, limiting or returning the movements of parts of a control mechanism, e.g. locking controlling member
- G05G5/12—Means for preventing, limiting or returning the movements of parts of a control mechanism, e.g. locking controlling member for holding members in an indefinite number of positions, e.g. by a toothed quadrant
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05G—CONTROL DEVICES OR SYSTEMS INSOFAR AS CHARACTERISED BY MECHANICAL FEATURES ONLY
- G05G5/00—Means for preventing, limiting or returning the movements of parts of a control mechanism, e.g. locking controlling member
- G05G5/12—Means for preventing, limiting or returning the movements of parts of a control mechanism, e.g. locking controlling member for holding members in an indefinite number of positions, e.g. by a toothed quadrant
- G05G5/14—Means for preventing, limiting or returning the movements of parts of a control mechanism, e.g. locking controlling member for holding members in an indefinite number of positions, e.g. by a toothed quadrant by locking a member with respect to a fixed quadrant, rod, or the like
- G05G5/16—Means for preventing, limiting or returning the movements of parts of a control mechanism, e.g. locking controlling member for holding members in an indefinite number of positions, e.g. by a toothed quadrant by locking a member with respect to a fixed quadrant, rod, or the like by friction
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05G—CONTROL DEVICES OR SYSTEMS INSOFAR AS CHARACTERISED BY MECHANICAL FEATURES ONLY
- G05G5/00—Means for preventing, limiting or returning the movements of parts of a control mechanism, e.g. locking controlling member
- G05G5/12—Means for preventing, limiting or returning the movements of parts of a control mechanism, e.g. locking controlling member for holding members in an indefinite number of positions, e.g. by a toothed quadrant
- G05G5/20—Means for preventing, limiting or returning the movements of parts of a control mechanism, e.g. locking controlling member for holding members in an indefinite number of positions, e.g. by a toothed quadrant by locking a quadrant, rod, or the like carried by the member
- G05G5/24—Means for preventing, limiting or returning the movements of parts of a control mechanism, e.g. locking controlling member for holding members in an indefinite number of positions, e.g. by a toothed quadrant by locking a quadrant, rod, or the like carried by the member by positive interengagement, e.g. by a pawl
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05G—CONTROL DEVICES OR SYSTEMS INSOFAR AS CHARACTERISED BY MECHANICAL FEATURES ONLY
- G05G2700/00—Control mechanisms or elements therefor applying a mechanical movement
- G05G2700/22—Mechanisms linking plurality of controlling or controlled members
- G05G2700/24—Locking controlled members of selectively controlled mechanisms
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T29/00—Metal working
- Y10T29/49—Method of mechanical manufacture
- Y10T29/49826—Assembling or joining
Definitions
- the invention relates to a steering system that provides a fail-soft operating mode during a transition between an autonomous steering mode and a driver-controlled steering mode, in particular in an emergency situation.
- U.S. Pat. No. 6,580,989 discloses a so-called hybrid-type steering system selectively operable in one of three modes: steer-by-wire, electronic power assist steering (EPAS), and manual steering.
- the steer-by-wire system includes a driver interface system (DIS), a road wheel actuator system (RWAS), and a controller for monitoring and implementing a preferred control strategy.
- the steering system operates normally in a steer-by-wire mode. Operation in the alternate EPAS mode and manual mode is determined by a controller in response to a malfunction in any part of either the DIS or the RWAS.
- the controller In each of the EPAS mode and manual mode, the controller causes a clutch mechanism to engage, thus creating a mechanical linkage between the steerable member and the rack and pinion system.
- the EPAS mode one of the road wheel actuator or the reaction torque generator is available to assist in the steering operation.
- both the DIS and the RWAS are deactivated and the vehicle is steerable through entirely mechanical means. As the driver is required to hold the steering wheel in all three operating modes, no particular measures have to be taken in the transition between the different steering modes.
- a steering system comprising a steering shaft and a brake mechanism movable between an released position and a engaged position for angularly locking the steering shaft, wherein the brake mechanism comprises an override such that a non-destructive external torque applied to the steering shaft above a given threshold when the brake mechanism is in the engaged position results in a rotation of the steering shaft.
- the brake mechanism can be moved to the engaged position for angularly locking the steering shaft mechanically linked to the ground wheels while the driver regains control of the steering wheel.
- the vehicle can be steered by applying on the steering wheel a torque above the threshold of the override.
- the override comprises a first friction element and a second friction element frictionally engaged with one another in the engaged position.
- the torque threshold for overriding the brake mechanism is given by the pressure between the first and second friction elements.
- the first friction element non-rotatable relative to the steering shaft, at least in the engaged position.
- the second friction element is non-rotatable relative to the brake mechanism in the engaged position.
- the second friction element may be rotatable relative to the brake mechanism in the released position and locked to the brake mechanism (and hence to a dashboard of the vehicle) to engage the brake.
- a biasing mechanism for engaging with one another the first and second friction elements.
- the biasing mechanism preferably comprises at least one biasing spring for applying a predetermined biasing force to at least one of the first and second friction elements.
- the predetermined biasing force is preferably such that the first and second friction elements start slipping upon application of a torque at least equal to the torque threshold.
- the torque threshold is preferably more than 1 Nm and less than 13 Nm.
- An adjustable abutment fixed at an adjustable position in relation to the steering shaft can be provided for loading the biasing spring.
- a particularly compact mechanism can be achieved if the biasing spring is a helicoidal spring wound around the steering shaft.
- the system can be tuned in various manners before it is mounted on the vehicle to define a desired torque threshold for the override: the material of the friction elements can be changed. If a biasing spring is provided, the stiffness of the spring can be changed. The easiest way of adapting the torque threshold without changing any of the parts of the steering system, however, is to change the location of the adjustable abutment.
- the brake mechanism comprises a first braking element, a second braking element, and an actuator, for engaging with one another the first and second braking elements in the locking position.
- the actuator is preferably an electromechanical actuator.
- At least one the first and second braking elements includes an annular interface in contact with the other of the first and second braking elements in the engaged position.
- the first and second braking elements are positively engaged with one another in the engaged position.
- at least one of the first and second braking elements may include an annular interface with a number of protrusions and/or recesses distributed over a circumference of the annular interface.
- the first and second braking elements are frictionally engaged with one another in the engaged position.
- the override comprises a friction dutch including a first friction element non-rotatable relative to the steering shaft and a second friction element non-rotatable relative to an annular interface of an annular braking element of the brake mechanism.
- the steering system may further comprise a bearing between the annular braking element and the steering shaft.
- a steering system comprising a steering shaft, a brake mechanism movable between an released position and a engaged position for angularly locking the steering shaft in several locking positions, and an override to allow rotation of the steering shaft upon application of a non-destructive external torque to the steering shaft above a given threshold when the brake mechanism is in the engaged position.
- a method of controlling a vehicle steering system during a transition from an autonomous operation mode to a manual mode wherein a steering shaft is locked at an actual position at the end of the autonomous operation mode and until a driver manually applies a torque above a given threshold on the steering wheel.
- FIG. 1 illustrates a steering system according to one embodiment of the invention
- FIG. 2 is an isometric view of a steering column of the steering system of FIG. 1 ;
- FIG. 3 is an exploded view of a part of the steering system of FIGS. 1 and 2 , showing the assembly of a braking system on the steering column;
- FIG. 4 is a more detailed exploded view of the braking system of FIG. 3 ;
- FIG. 5 is a section of a steering shaft and of the braking system of FIG. 3 ;
- FIG. 6 is a section of an alternative embodiment of the braking system
- FIG. 7 illustrates an alternative embodiment of the steering system.
- a vehicle is provided with a steering system 10 including a steering wheel 12 , a steering shaft 14 , a pinion gear 16 that rotates with the steering shaft 14 and meshes with a toothed rack 18 for moving tie rods 20 linked to steerable ground wheels 22 .
- the steering wheel 12 is connected to the steering shaft through a mechanical or electrical clutch mechanism 26 .
- a steering motor 28 is connected with the steering shaft and controlled by a steering control unit 30 .
- Rotation and/or torque sensors 32 , 34 are provided on the steering wheel 12 and on the steering shaft 14 and connected to the control unit 30 .
- this steering system 10 is known from US 2013002416, which is incorporated herewith by reference.
- the steering system 10 is further provided with a friction brake mechanism 36 , which is illustrated in detail in FIGS. 2 to 5 .
- the brake mechanism 36 comprises an actuator 38 received in an actuator housing 40 clamped with a C-shaped clamp 42 to a jacket tube 44 in which the steering shaft 14 is mounted for rotation about a steering axis 100 .
- the actuator 38 which can be of any suitable construction, moves a toothed lock bolt 46 back and forth against a toothed sleeve 48 in a radial direction respective to the steering axis 100 .
- a needle bearing 50 is provided to guide the toothed sleeve 48 in rotation about the steering axis 100 .
- the toothed sleeve 48 is pressed fitted onto an outer race ring of the needle bearing.
- the toothed sleeve has a first annular planar face 52 in frictional contact with a flat abutment ring 54 press-fitted onto the steering shaft 14 , and a second annular face 56 opposed to the first annular face 52 .
- a compression spring 58 is loaded between the second annular face 56 and an adjustable thrust washer 60 , which is connected to the steering shaft 14 by press-fitting at a proper distance from the abutment ring 54 to achieve a desired axial force through the compression spring 58 at the interface between the toothed sleeve 48 and the abutment ring 54 .
- the brake mechanism does not impart any axial thrust on the steering shaft, since both the adjustable thrust washer and the abutment ring sit on the steering shaft.
- a switch 62 may be provided to allow the driver to switch between a driver-controlled steering mode and an autonomous steering mode. This switch 62 may be located on the dashboard or integrated to the steering wheel 12 , e.g. as disclosed in US2013002416.
- the brake mechanism In the driver-controlled steering mode and in the autonomous steering mode, the brake mechanism is disengaged, i.e. the toothed lock bolt 46 is out of engagement with the toothed sleeve 48 , which can rotate together with the abutment ring 54 , the compression spring 58 , the adjustable thrust washer 60 and the steering shaft 14 as one unit.
- the clutch 26 In the driver-controlled steering mode, the clutch 26 is engaged and the steering wheel 12 is mechanically connected to the steering shaft 14 and the ground wheels 22 .
- the motor 28 may or may not be used as power assistance for supplementing the torque delivered by the driver on the steering wheel 12 .
- the clutch 26 is disengaged and the motor 28 applies a driving torque to the steering shaft 14 irrespective of the position of the steering wheel 12 .
- the driver may regain at least partial control of the steering by turning the steering wheel 12 by a predetermined angle, which is detected by the sensor 32 .
- a haptic feedback (e.g. click) may be provided to inform the driver that his or her request to regain partial or total control of the steering system 10 has been registered and executed.
- Various transition strategies can be configured in response to the input of the driver and of various other parameters of the vehicle: the clutch 26 may or may not remain disengaged, and if not, the motor 28 may or may not be used as power steering assistance.
- the autonomous steering control unit 30 If on the other hand the autonomous steering mode has to be interrupted as a matter of urgency at the initiative of the steering control unit 30 , e.g. because of a malfunction of the motor 28 or of a sensor, before the driver has had time to regain control of the steering, the autonomous steering control unit generates an alarm to inform the driver and at the same time reengages the dutch 26 and the brake mechanism 36 .
- the toothed lock bolt 46 engages the toothed sleeve 48 so as to prevent its rotation.
- the toothed sleeve 48 is biased by the loaded compression spring 58 in frictional engagement with the flat abutment ring 54 and prevents rotation of the steering shaft 14 .
- the rack and pinion transmission 18 , 16 , tie rods 20 and ground wheels 22 remain in the position assumed at the beginning of the transition, to give the driver time to regain control of the steering wheel 12 .
- the sensor 32 detects the applied torque and the control unit disengages the toothed lock bolt 46 to release the steering shaft 14 . Should however the toothed lock bolt 46 remain engaged, e.g.
- the driver can override the brake mechanism 36 by applying a torque that is higher than the rated frictional torque resulting from the axial force of the compression spring 58 onto the toothed sleeve 48 , to maneuver the vehicle to a full stop in a fail-soft mode.
- the brake mechanism 36 remains engaged, which means that the driver has to continuously overcome the rated frictional torque of the brake mechanism.
- the rated frictional torque of the brake mechanism should preferably be both of a sufficient magnitude to prevent rotation of the steering shaft before the driver has gripped the steering wheel, and sufficiently low to allow the driver to turn the steering wheel.
- the brake mechanism 36 is mounted on a sleeve 70 to create a stand-alone module.
- the sleeve 70 can be press fitted or welded on the steering shaft 14 .
- the brake mechanism 36 is inserted in a steering system 10 without clutch, including a steering wheel 12 , a steering shaft 14 , a pinion gear 16 that rotates with the steering shaft 14 and meshes with a toothed rack 18 for moving tie rods 20 linked to steerable ground wheels 22 .
- a steering motor 28 is connected with the steering shaft and controlled by a steering control unit 30 .
- the steering wheel 12 is connected to a feedback motor 80 .
- Rotation and/or torque sensors 32 , 34 are provided on the steering wheel 12 and on the steering shaft 14 and connected to the control unit 30 .
- the compression spring 58 can be replaced with a Belleville washer.
- the bearing 50 for guiding the toothed sleeve can be of any type, e.g. a roller bearing with or without cage, or a sliding bearing to achieve weight reduction or meet space requirements. Tuning can be achieved by proper selection of the materials and surface roughness or friction coefficient at the friction interface between the flat abutment ring 54 and the toothed sleeve 48 .
- plastic, rubber, ceramic and/or organic resin can be used as well as steel.
- the adjustable thrust washer and/or abutment ring can be replaced with nuts if the shaft has provision for external threads. This allows a very precise tuning of the slipping torque.
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Automation & Control Theory (AREA)
- Steering Control In Accordance With Driving Conditions (AREA)
- Power Steering Mechanism (AREA)
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- Manufacturing & Machinery (AREA)
Abstract
Description
- The invention relates to a steering system that provides a fail-soft operating mode during a transition between an autonomous steering mode and a driver-controlled steering mode, in particular in an emergency situation.
- To address the issue of an ergonomic and intuitive voluntary transition from an autonomous steering mode to manual steering, it has been suggested in US 2013 002416 to provide a vehicle steering system with an autonomous interface steering wheel movable from a first position to a second position and an autonomous driving electronic control unit configured to receive a signal indicating that the autonomous interface steering wheel has been moved from the first position to the second position and initiate change of operation of the vehicle between the manual steering mode and the autonomous steering mode in response to receiving the signal. However, this system does not address the issue of a safe transition from the autonomous steering mode to the manual or driver-controlled steering mode at the initiative of the autonomous driving electronic control unit, e.g. in an emergency situation.
- In a somewhat different context, U.S. Pat. No. 6,580,989 discloses a so-called hybrid-type steering system selectively operable in one of three modes: steer-by-wire, electronic power assist steering (EPAS), and manual steering. The steer-by-wire system includes a driver interface system (DIS), a road wheel actuator system (RWAS), and a controller for monitoring and implementing a preferred control strategy. The steering system operates normally in a steer-by-wire mode. Operation in the alternate EPAS mode and manual mode is determined by a controller in response to a malfunction in any part of either the DIS or the RWAS. In each of the EPAS mode and manual mode, the controller causes a clutch mechanism to engage, thus creating a mechanical linkage between the steerable member and the rack and pinion system. In the EPAS mode, one of the road wheel actuator or the reaction torque generator is available to assist in the steering operation. Alternatively, in the manual mode, both the DIS and the RWAS are deactivated and the vehicle is steerable through entirely mechanical means. As the driver is required to hold the steering wheel in all three operating modes, no particular measures have to be taken in the transition between the different steering modes.
- Accordingly, there is a need for means to ensure a safe transition from an autonomous steering to a driver-controlled steering in a vehicle when the driver is unaware of the imminence of this transition.
- According to one aspect of the invention, there is provided a steering system comprising a steering shaft and a brake mechanism movable between an released position and a engaged position for angularly locking the steering shaft, wherein the brake mechanism comprises an override such that a non-destructive external torque applied to the steering shaft above a given threshold when the brake mechanism is in the engaged position results in a rotation of the steering shaft. During a transition from an autonomous steering mode to driver-controlled steering mode, the brake mechanism can be moved to the engaged position for angularly locking the steering shaft mechanically linked to the ground wheels while the driver regains control of the steering wheel. Once the hands of the driver are on the steering wheel, the vehicle can be steered by applying on the steering wheel a torque above the threshold of the override.
- According to a preferred embodiment, the override comprises a first friction element and a second friction element frictionally engaged with one another in the engaged position. The torque threshold for overriding the brake mechanism is given by the pressure between the first and second friction elements. According to one embodiment, the first friction element non-rotatable relative to the steering shaft, at least in the engaged position. The second friction element is non-rotatable relative to the brake mechanism in the engaged position. The second friction element may be rotatable relative to the brake mechanism in the released position and locked to the brake mechanism (and hence to a dashboard of the vehicle) to engage the brake.
- According to a preferred embodiment, a biasing mechanism is provided for engaging with one another the first and second friction elements. The biasing mechanism preferably comprises at least one biasing spring for applying a predetermined biasing force to at least one of the first and second friction elements. The predetermined biasing force is preferably such that the first and second friction elements start slipping upon application of a torque at least equal to the torque threshold. The torque threshold is preferably more than 1 Nm and less than 13 Nm. An adjustable abutment fixed at an adjustable position in relation to the steering shaft can be provided for loading the biasing spring. A particularly compact mechanism can be achieved if the biasing spring is a helicoidal spring wound around the steering shaft.
- As will be readily understood, the system can be tuned in various manners before it is mounted on the vehicle to define a desired torque threshold for the override: the material of the friction elements can be changed. If a biasing spring is provided, the stiffness of the spring can be changed. The easiest way of adapting the torque threshold without changing any of the parts of the steering system, however, is to change the location of the adjustable abutment.
- According to one embodiment, the brake mechanism comprises a first braking element, a second braking element, and an actuator, for engaging with one another the first and second braking elements in the locking position. The actuator is preferably an electromechanical actuator.
- According to one embodiment, at least one the first and second braking elements includes an annular interface in contact with the other of the first and second braking elements in the engaged position.
- According to one aspect of the invention, the first and second braking elements are positively engaged with one another in the engaged position. In particular, at least one of the first and second braking elements may include an annular interface with a number of protrusions and/or recesses distributed over a circumference of the annular interface.
- According to another aspect of the invention, the first and second braking elements are frictionally engaged with one another in the engaged position.
- According to one embodiment, the override comprises a friction dutch including a first friction element non-rotatable relative to the steering shaft and a second friction element non-rotatable relative to an annular interface of an annular braking element of the brake mechanism. The steering system may further comprise a bearing between the annular braking element and the steering shaft.
- According to another aspect of the invention, there is provided a steering system comprising a steering shaft, a brake mechanism movable between an released position and a engaged position for angularly locking the steering shaft in several locking positions, and an override to allow rotation of the steering shaft upon application of a non-destructive external torque to the steering shaft above a given threshold when the brake mechanism is in the engaged position.
- According to another aspect of the invention, there is provided a method of controlling a vehicle steering system during a transition from an autonomous operation mode to a manual mode, wherein a steering shaft is locked at an actual position at the end of the autonomous operation mode and until a driver manually applies a torque above a given threshold on the steering wheel.
- Other advantages and features of the invention will become more clearly apparent from the following description of specific embodiments of the invention given as non-restrictive examples only and represented in the accompanying drawings, in which:
-
FIG. 1 illustrates a steering system according to one embodiment of the invention; -
FIG. 2 is an isometric view of a steering column of the steering system ofFIG. 1 ; -
FIG. 3 is an exploded view of a part of the steering system ofFIGS. 1 and 2 , showing the assembly of a braking system on the steering column; -
FIG. 4 is a more detailed exploded view of the braking system ofFIG. 3 ; -
FIG. 5 is a section of a steering shaft and of the braking system ofFIG. 3 ; -
FIG. 6 is a section of an alternative embodiment of the braking system; -
FIG. 7 illustrates an alternative embodiment of the steering system. - Corresponding reference numerals refer to the same or corresponding parts in each of the figures.
- Referring to
FIG. 1 , a vehicle is provided with asteering system 10 including asteering wheel 12, asteering shaft 14, apinion gear 16 that rotates with thesteering shaft 14 and meshes with atoothed rack 18 for movingtie rods 20 linked tosteerable ground wheels 22. Thesteering wheel 12 is connected to the steering shaft through a mechanical orelectrical clutch mechanism 26. Asteering motor 28 is connected with the steering shaft and controlled by asteering control unit 30. Rotation and/ortorque sensors steering wheel 12 and on thesteering shaft 14 and connected to thecontrol unit 30. As such, thissteering system 10 is known from US 2013002416, which is incorporated herewith by reference. - The
steering system 10 is further provided with afriction brake mechanism 36, which is illustrated in detail inFIGS. 2 to 5 . Thebrake mechanism 36 comprises anactuator 38 received in anactuator housing 40 clamped with a C-shaped clamp 42 to ajacket tube 44 in which thesteering shaft 14 is mounted for rotation about asteering axis 100. Theactuator 38, which can be of any suitable construction, moves atoothed lock bolt 46 back and forth against atoothed sleeve 48 in a radial direction respective to thesteering axis 100. A needle bearing 50 is provided to guide thetoothed sleeve 48 in rotation about thesteering axis 100. Thetoothed sleeve 48 is pressed fitted onto an outer race ring of the needle bearing. The toothed sleeve has a first annularplanar face 52 in frictional contact with aflat abutment ring 54 press-fitted onto thesteering shaft 14, and a secondannular face 56 opposed to the firstannular face 52. Acompression spring 58 is loaded between the secondannular face 56 and anadjustable thrust washer 60, which is connected to the steeringshaft 14 by press-fitting at a proper distance from theabutment ring 54 to achieve a desired axial force through thecompression spring 58 at the interface between thetoothed sleeve 48 and theabutment ring 54. As will be apparent to those skilled in the art, the brake mechanism does not impart any axial thrust on the steering shaft, since both the adjustable thrust washer and the abutment ring sit on the steering shaft. - A
switch 62 may be provided to allow the driver to switch between a driver-controlled steering mode and an autonomous steering mode. Thisswitch 62 may be located on the dashboard or integrated to thesteering wheel 12, e.g. as disclosed in US2013002416. - In the driver-controlled steering mode and in the autonomous steering mode, the brake mechanism is disengaged, i.e. the
toothed lock bolt 46 is out of engagement with thetoothed sleeve 48, which can rotate together with theabutment ring 54, thecompression spring 58, theadjustable thrust washer 60 and the steeringshaft 14 as one unit. - In the driver-controlled steering mode, the clutch 26 is engaged and the
steering wheel 12 is mechanically connected to the steeringshaft 14 and theground wheels 22. Themotor 28 may or may not be used as power assistance for supplementing the torque delivered by the driver on thesteering wheel 12. - In the autonomous steering mode, the clutch 26 is disengaged and the
motor 28 applies a driving torque to the steeringshaft 14 irrespective of the position of thesteering wheel 12. In the autonomous steering mode, the driver may regain at least partial control of the steering by turning thesteering wheel 12 by a predetermined angle, which is detected by thesensor 32. A haptic feedback (e.g. click) may be provided to inform the driver that his or her request to regain partial or total control of thesteering system 10 has been registered and executed. Various transition strategies can be configured in response to the input of the driver and of various other parameters of the vehicle: the clutch 26 may or may not remain disengaged, and if not, themotor 28 may or may not be used as power steering assistance. - If on the other hand the autonomous steering mode has to be interrupted as a matter of urgency at the initiative of the
steering control unit 30, e.g. because of a malfunction of themotor 28 or of a sensor, before the driver has had time to regain control of the steering, the autonomous steering control unit generates an alarm to inform the driver and at the same time reengages the dutch 26 and thebrake mechanism 36. Thetoothed lock bolt 46 engages thetoothed sleeve 48 so as to prevent its rotation. Thetoothed sleeve 48 is biased by the loadedcompression spring 58 in frictional engagement with theflat abutment ring 54 and prevents rotation of the steeringshaft 14. As a result, the rack andpinion transmission tie rods 20 andground wheels 22 remain in the position assumed at the beginning of the transition, to give the driver time to regain control of thesteering wheel 12. As soon as the driver imparts torque to thesteering wheel 12, thesensor 32 detects the applied torque and the control unit disengages thetoothed lock bolt 46 to release the steeringshaft 14. Should however thetoothed lock bolt 46 remain engaged, e.g. because of a malfunction of thesensor 32, of theactuator 38 or of thecontrol unit 30, the driver can override thebrake mechanism 36 by applying a torque that is higher than the rated frictional torque resulting from the axial force of thecompression spring 58 onto thetoothed sleeve 48, to maneuver the vehicle to a full stop in a fail-soft mode. During this man oeuvre, thebrake mechanism 36 remains engaged, which means that the driver has to continuously overcome the rated frictional torque of the brake mechanism. For this reason, the rated frictional torque of the brake mechanism should preferably be both of a sufficient magnitude to prevent rotation of the steering shaft before the driver has gripped the steering wheel, and sufficiently low to allow the driver to turn the steering wheel. - In the embodiment illustrated in
FIG. 6 , thebrake mechanism 36 is mounted on asleeve 70 to create a stand-alone module. Thesleeve 70 can be press fitted or welded on the steeringshaft 14. - In the embodiment of
FIG. 7 , thebrake mechanism 36 is inserted in asteering system 10 without clutch, including asteering wheel 12, a steeringshaft 14, apinion gear 16 that rotates with the steeringshaft 14 and meshes with atoothed rack 18 for movingtie rods 20 linked tosteerable ground wheels 22. Asteering motor 28 is connected with the steering shaft and controlled by asteering control unit 30. Thesteering wheel 12 is connected to afeedback motor 80. Rotation and/ortorque sensors steering wheel 12 and on the steeringshaft 14 and connected to thecontrol unit 30. - Various other modifications are contemplated. Depending on the packaging area available, the
compression spring 58 can be replaced with a Belleville washer. The bearing 50 for guiding the toothed sleeve can be of any type, e.g. a roller bearing with or without cage, or a sliding bearing to achieve weight reduction or meet space requirements. Tuning can be achieved by proper selection of the materials and surface roughness or friction coefficient at the friction interface between theflat abutment ring 54 and thetoothed sleeve 48. In particular, plastic, rubber, ceramic and/or organic resin can be used as well as steel. The adjustable thrust washer and/or abutment ring can be replaced with nuts if the shaft has provision for external threads. This allows a very precise tuning of the slipping torque.
Claims (21)
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US14/149,309 US9669864B2 (en) | 2014-01-07 | 2014-01-07 | Friction brake mechanism and associated steering column |
FR1462562A FR3016152B1 (en) | 2014-01-07 | 2014-12-17 | FRICTION BRAKE MECHANISM AND STEERING COLUMN THEREFOR |
DE102014226154.6A DE102014226154B4 (en) | 2014-01-07 | 2014-12-17 | Friction braking mechanism and associated steering column |
Applications Claiming Priority (1)
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US14/149,309 US9669864B2 (en) | 2014-01-07 | 2014-01-07 | Friction brake mechanism and associated steering column |
Publications (2)
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US20150191198A1 true US20150191198A1 (en) | 2015-07-09 |
US9669864B2 US9669864B2 (en) | 2017-06-06 |
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US14/149,309 Active 2034-09-04 US9669864B2 (en) | 2014-01-07 | 2014-01-07 | Friction brake mechanism and associated steering column |
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US (1) | US9669864B2 (en) |
DE (1) | DE102014226154B4 (en) |
FR (1) | FR3016152B1 (en) |
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US9630644B2 (en) | 2013-03-15 | 2017-04-25 | Ford Global Technologies, Llc | Method and system for stowing steering column in an autonomous vehicle |
CN106828588A (en) * | 2015-12-03 | 2017-06-13 | 联创汽车电子有限公司 | Electric boosting steering system unmanned steering control method |
WO2018093878A1 (en) * | 2016-11-17 | 2018-05-24 | Robert Bosch Automotive Steering Llc | Friction clutch mechanism |
CN111801268A (en) * | 2018-01-04 | 2020-10-20 | 乔伊森安全系统收购有限责任公司 | System and method for autonomous front wheel steering |
US10843709B2 (en) | 2015-11-30 | 2020-11-24 | Bayerische Motoren Werke Aktiengesellschaft | Arrangement, vehicle and method for having an occupant of a vehicle that is in a highly automated driving mode take over a driving task |
US11105330B2 (en) | 2018-08-29 | 2021-08-31 | Borgwarner Inc. | Power transmitting component having a shaft with a circumferential channel communicating fluid between a shaft-driven pump and a feed conduit formed in the shaft |
CN114684246A (en) * | 2020-12-30 | 2022-07-01 | 比亚迪股份有限公司 | Vehicle steering system and vehicle with same |
US20230033041A1 (en) * | 2019-11-20 | 2023-02-02 | Robert Bosch Gmbh | Method for Operating a Vehicle |
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US9481393B1 (en) * | 2015-12-22 | 2016-11-01 | Uber Technologies, Inc. | Integrated clutch steering system |
DE102019102069A1 (en) * | 2019-01-28 | 2020-07-30 | Bayerische Motoren Werke Aktiengesellschaft | Switchable clutch for a steer-by-wire steering system, steer-by-wire steering system, method for operation and vehicle |
DE102021201431A1 (en) | 2021-02-16 | 2022-08-18 | Thyssenkrupp Ag | Auxiliary power drive for introducing an auxiliary torque into a steering shaft of a motor vehicle steering system and method for producing an auxiliary power drive |
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Cited By (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US9630644B2 (en) | 2013-03-15 | 2017-04-25 | Ford Global Technologies, Llc | Method and system for stowing steering column in an autonomous vehicle |
US10843709B2 (en) | 2015-11-30 | 2020-11-24 | Bayerische Motoren Werke Aktiengesellschaft | Arrangement, vehicle and method for having an occupant of a vehicle that is in a highly automated driving mode take over a driving task |
CN106828588A (en) * | 2015-12-03 | 2017-06-13 | 联创汽车电子有限公司 | Electric boosting steering system unmanned steering control method |
WO2018093878A1 (en) * | 2016-11-17 | 2018-05-24 | Robert Bosch Automotive Steering Llc | Friction clutch mechanism |
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CN111801268A (en) * | 2018-01-04 | 2020-10-20 | 乔伊森安全系统收购有限责任公司 | System and method for autonomous front wheel steering |
US11105330B2 (en) | 2018-08-29 | 2021-08-31 | Borgwarner Inc. | Power transmitting component having a shaft with a circumferential channel communicating fluid between a shaft-driven pump and a feed conduit formed in the shaft |
US20230033041A1 (en) * | 2019-11-20 | 2023-02-02 | Robert Bosch Gmbh | Method for Operating a Vehicle |
US11807317B2 (en) * | 2019-11-20 | 2023-11-07 | Robert Bosch Gmbh | Method for operating a vehicle |
CN114684246A (en) * | 2020-12-30 | 2022-07-01 | 比亚迪股份有限公司 | Vehicle steering system and vehicle with same |
WO2022143807A1 (en) * | 2020-12-30 | 2022-07-07 | 比亚迪股份有限公司 | Vehicle steering system, and vehicle having same |
Also Published As
Publication number | Publication date |
---|---|
DE102014226154B4 (en) | 2022-12-08 |
FR3016152B1 (en) | 2019-05-31 |
FR3016152A1 (en) | 2015-07-10 |
US9669864B2 (en) | 2017-06-06 |
DE102014226154A1 (en) | 2015-07-23 |
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